1. Field of the Invention
This invention relates to a television camera lens diagnostic system, and more particularly to a system for diagnosing the state of movable mechanism in a television camera lens such as a focusing mechanism, a zoom mechanism and the like.
2. Description of the Prior Art
In a TV camera used in a television station and the like, a lens unit having therein a plurality of movable mechanisms such as a focusing mechanism, a zoom mechanism, an iris mechanism and the like is mounted on the front side of the camera. Since the state of operation of these movable mechanisms immediately affects the image quality, the state of operation of the movable mechanisms must be constantly checked.
However since a large number of cameras are used in the TV station and further each lens unit has a substantial number of movable mechanisms, checking the state of the operation of the movable mechanisms is very troublesome.
The system disclosed in Japanese Patent Application No. 5(1993)-109098 discloses a zoom lens that is moved from telephoto to wide-angle positions. The moving speed, value of electric current, and the like are measured in predetermined positions during operation to detect failures. If an error is detected, a failure condition is indicated.
The system can save labor of the operator and shorten the time for checking. Further when such checking is made by an unskilled operator, reliability of the checking can be improved by use of the system.
However, if there is found any trouble, it will be helpful to know the specific part or sub-unit where trouble exists. For example, since in the case of the lens unit for a TV camera, trouble can develop in various parts, such as a signal input circuit, amplifiers, electric motors, mechanical parts, and the like, it will be helpful when the operator can know the troubled part at a glance.
Further, the lens unit need not be perfect in practical use depending on the extent of the trouble, the part of trouble or the way of use. For example, in the case of a zoom lens, depending on the shooting situation, the cameraman's sense or the like, the lens is used only in a part of its focal length range. In such a case, trouble in the zooming system outside the use focal length range does not cause any problem in practical use, and accordingly, the trouble may be taken care of later.
Further even if the driving current for the lens driving motor deviates from the reference value, it sometimes causes no problem in practical use.
The same is true of other movable mechanisms such as the focusing mechanism, the extender mechanism, the iris mechanism and the like.